This invention relates generally to jet outboard propulsion steering apparatus, and in particular to steering apparatus for watercraft operating in very shallow water.
On many occassions, jet outboard propelled watercraft are called upon to operate in very shallow water, approximately 1-3 inches (2 to 7 centimeters) deep, while the boat hull is planing along the surface of the water.
Where the inlet port of the jet propulsion apparatus depends downwardly to a level proximate the extended bottom surface of the boat hull, or just below, there is a strong tendency for rocks, gravel and other debris to be drawn into the inlet port of the jet propulsion apparatus in such shallow water. Where the inlet port extends below the boat hull, rocks and gravel are actually scooped up into the jet pump if the boat should run aground in shallow water. Raising the inlet port above the bottom of the boat hull removes the rock scooping problem and reduces the tendency to lift rocks and debris by suction from the bed of the river, lake or ocean. Such debris can cause jamming and serious damage to the jet drive apparatus.
If, to avoid these problems, the inlet ports of the prior art jet propelled boats were raised above the extended bottom surface of the hull, as soon as the hull of these prior art jet propelled boats started to plane along the surface of the water at high speeds, the jet propulsion apparatus would become water-starved and fail to properly propel the watercraft.
The inventors of the water jet propulsion devices of the prior art were apparently not yet confronted with these problems and, being content with having eliminated the damage prone propeller, placed the inlet port of their jet propulsion apparatus even with or below the underside of the boat hull.
Also, many of the prior art jet propulsion devices had their inlet ports disposed facing the surface of the water whereby the plane defined by the face of the inlet port was parallel to the water surface.
In some cases, the inlet port was disposed in a channel in the boat hull, however, with the inlet port having its inlet port face parallel with the surface of the water and also even with the extended bottom surface of the boat hull.
There was no indication, with respect to the prior art devices, that they were to be operated in very shallow water only inches deep, and over rocky or gravel bottoms of rivers or lakes.
Under these circumstances, shallow water operation of such prior art jet drive devices would result in rocks and debris being sucked up or drawn into the drive mechanism causing damage to the apparatus.